Add sound to animation preview
To get 3D Sound you could add a Speaker to the scene



and choose the sound file in the Properties window



You can adjust the playback time in the NLA editor:



Or as another variant you could just use the Video Sequence Editor and add a sound file there. This will be plain playback with no positional audio.



The synchronization of audio and video/viewport playback can be set in the timeline. AV-sync will drop frames in the viewport if the scene is too heavy, so the timing will still be correct.